Oct 2020 Observing Notes
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Observing Notes - October 2020 Get ‘em while you can! This time of year as the dark skies arrive earlier and earlier, astronomers and particularly astrophotographers are eagerly awaiting the rise of Orion as this easily recognisable constellation peaks its head above the horizon at midnight and heralds the imminent arrival of colder clear nights and the easiest nebula to see in the skies; M42. However this time of year also carries other great sites in to the night skies and not all of them are faint fuzzies, so before they dip down to the murky horizon or even disappear from our skies until spring the following sites. Deep Sky Objects (Closest to the horizon first) Messier 10 (M10) is a rich, bright globular cluster located in the constellation Ophiuchus. 5 With a visual magnitude of 6.4, even Looking South West to M10 and M12 the cluster’s bright core is too faint to be sky from Messier seen without binoculars. 10. Both clusters (M10 and M12) A small telescope (3-inch) will reveal can be found about half the cluster’s size; roughly 8 to about half a 9 minutes of arc, its bright central fistwidth west of region. Larger telescopes show the the bright star cluster extending across 15.1 arc Beta Ophiuchi, minutes and reveal a large, bright also known as central core. Cebalrai, with In reality, the cluster is about two Messier 10 lying a thirds the size of the full Moon, but its bit lower in the outer regions are very dim and invisible sky, to the south of except in very large telescopes. M12. M10 lies along the line Messier 12 (M12), also known as the from Cebalrai to Gumball Globular, is a globular star Zeta Ophiuchi, the 5Messier12 cluster is also located in the third brightest star in Ophiuchus. It is only a degree away constellation Ophiuchus. from 30 Ophiuchi, an orange giant star with an apparent Messier 12 is invisible to the naked magnitude of 4.8. eye, but can be seen with binoculars in In the constellation of Aquarius is NGC 7293, the Helix good conditions, with clear dark skies Nebula, which is also listed as Caldwell C63. It is a planetary and no light pollution. Stars in the nebular around magnitude 7.6 so it should be the easy to spot. cluster can be resolved with an 8-inch or However, it will be this month’s biggest challenge as it never larger telescope. A 10-inch instrument gets very high from UK locations so you will need both very reveals the core with a diameter of 3 arc good seeing and a clear view looking south at 10pm to spot it. minutes and a halo of stars stretching across an area of 10 arc minutes. Start at the 3rd magnitude star Delta (δ) Aquarii. look 4° southwest for 5th magnitude 66 Aquarii. It should fit in the The cluster lies about 3 degrees in the same finder field with Delta and shine with an orange tint. Observing Notes - October 2020 : Get ‘em while you can! Page 2 5Helix and Saturn Nebulae Continue along that line another 2.8° and you will come to yellow-white Upsilon (υ) Aquarii, the brightest star in the area at magnitude 5.2. The Helix sits 1.2° west of Upsilon and is best sought with a low-power eyepiece. Two 10th-magnitude stars lie halfway between, helping pinpoint the Helix in two easy jumps. NGC 7009 or Caldwell C55 is also in Aquarius and is known as the Saturn Nebula because it appears to have ‘ears’ and perhaps looks a bit like how Galileo would have first seen the planet Saturn and its rings. It shines at around mag 8 so should be detectable in even a small telescope, especially with its greenish glow. The Saturn Nebula lies in the western corner of Aquarius, just over a degree west of 4th magnitude Nu (ν) Aquarii. 5Messier 13 and 92 across 20 arc minutes of the sky and easily visible Just as a side note the asterism M73 is 2 degrees in binoculars or a small scope. southwest of the Saturn Nebula, with 9th magnitude globular cluster M72 a further 1.5 Messier 92 (M92) is another a globular cluster degrees west of M73 should you want to try those located in the northern constellation Hercules. It also. is positioned north of the Keystone asterism in Hercules, between the Keystone star Eta Herculis Messier 13 (M13), also known as the Great and Iota Herculis. Globular Cluster in Hercules, and is (funny enough) a globular cluster located in Hercules. In 10×50 binoculars, M92 appears like a blurry star with a brighter core. Small and medium-sized The 5.8 magnitude cluster can be seen without telescopes will resolve some of the stars in the binoculars in exceptionally good viewing outer regions of the cluster. 6-inch and 8-inch conditions, with clear skies and no light pollution. telescopes show an oval-shaped cluster with a It can be found about a 3rd of the way along a bright centre, surrounded by a halo of stars. 12- line drawn between the right-hand keystone inch telescopes resolve dozens of individual stars asterism stars η and ζ Herculis and stretches in the halo and throughout the cluster. Observing Notes - October 2020 : Get ‘em while you can! Page 3 The cluster lies about 60 percent of the way The Ring Nebula has a magnitude of 8.8 and from Eta to Iota. It forms a triangle with the two lies to the south of Vega, the brightest star in Lyra northernmost stars of the Keystone, Eta and Pi and one of the stars that form the Summer Herculis and can be found by first locating the Triangle. The nebula is easy to find as it is located bright Etamin (Eltanin, Gamma Draconis), an roughly 40 percent of the distance from Sheliak, orange giant in Draco, and then moving about 6 Beta Lyrae, to Sulafat, Gamma Lyrae. degrees in the direction of the Keystone. Unfortunately, the nebula cannot be resolved in small binoculars but small telescopes will reveal the nebula’s ring shape, but the nebula is best seen in 8-inch and larger telescopes. The Solar System The Moon October 1 - Full Hunters Moon is named because at this time of year the leaves are falling and the game is fat and ready to hunt... apparently. Other names are the Travel Moon and the Blood Moon and the Harvest Moon. The Harvest Moon is the full moon that occurs closest to the September equinox each year. Personally I think there is more interest in observing the texture of the moon surface around terminator during the waxing and waning phases. On October 16 the Moon is new and will not be visible in the night sky so this is the best time of the month to observe faint objects such as galaxies and star clusters 5Messier 57 The Planets Messier 57 (M57) is known as the Ring Nebula and is a planetary nebula located in the northern October 1 - Mercury is at its Greatest Eastern constellation Lyra. Elongation from the Sun but it is very low in the sky from the UK making observing very difficult. 5Mars, Jupiter and Saturn Observing Notes - October 2020 : Get ‘em while you can! Page 4 Venus rises in the constellation of Leo at about 03:30 at the unusual shower in that the best viewing beginning of the month, a good three hours before sunrise, so is in the early evening instead of early is easily observable for the early risers. morning like most other showers. October 13 - Mars will be at its closest approach to Earth The shower runs annually from and its face will be fully illuminated by the Sun. It will be October 6-10 and peaks on the night of brighter than any other time of the year and will be visible all the 7th. The moon will be at last quarter night long. Located in the constellation of Pisces, this is the so will help the early evening observers best time to view and photograph Mars. A medium-sized see meteors radiate from the telescope will allow you to see some of the dark details on the constellation Draco. planet's orange surface. October 21, 22 - Orionids Meteor Both Jupiter and Saturn are still visible to the south but are Shower. The Orionids produces up to 20 getting closer to the western horizon as the month passes. Still meteors per hour at its peak. It is a magnificent site even in smaller telescope the mirk of the produced by dust grains left behind by horizon means the seeing good surface detail is becoming less comet Halley, which has been known likely. and observed since ancient times. The shower runs annually from October 2 to November 7. It peaks this year on the night of the 21st in to the 22nd. The moon is a waxing crescent setting before midnight when the meteors will appear to radiate from the constellation Orion. Lastly, clocks go back on the 25th of the month so we can enjoy the night skies even earlier. Chris Brooks WAS ObservingTeam 5UranusOn October 31 the blue-green planet Uranus will be at its closest approach to Earth visible all night long in the constellation of Aries. This is the best time to view Uranus. Due to its distance, it will only appear as a tiny blue-green dot in all but the most powerful telescopes.